Known methods for reducing the organic contaminants were predicated upon treating in a liquid state the condensed water that results from the energy recovery step of the closed loop drying system.
The disadvantage of the current state of the art is that the contaminants must be removed while the material is handled in a liquid state. To achieve water quality level suitable for commercial reuse or discharge to sewer often requires multiple physical separation and chemical treatment steps. As a result, the capital cost of the equipment is generally higher in comparison to treating the emissions in a vapor state using a single, highly efficient, thermal step that can be integrated into the closed loop drying system between the dryer and the energy recovery step.
The above described disadvantages impose increased economic requirements in capital investments in water treatment facilities and in the requirements of increased footprint in terms of plant space. Furthermore, the energy utilization in the water treatment cannot be partially recovered as can the thermal treatment of the organics in the regenerative thermal oxidizer prior to the energy recovery step. Different waste water treatment strategies and pre-existing waste water treatment facilities can reduce the closed loop dryer condensate costs on a per gallon basis. For a new installation, however, it is extremely difficult to offset the capital cost disadvantage of water treatment as opposed to the innovation of using an integrated regenerative thermal oxidizer to treat the organics prior to the energy recovery.